1. Field of the Invention
The present invention relates to a linear actuator.
2. Discussion of the Background
Unexamined Japanese patent publication (Kokai) Hei 11-341778 discloses a linear actuator. The contents of this application are incorporated herein by reference in their entirety.
Referring to FIG. 1, the linear actuator 2 includes a cylindrical stator 4, a coil 6, and a moving part 8 which is linearly movable. The stator 4 includes first and second permanent magnets (10 and 12). The cross-sections of the permanent magnets (10 and 12) are rectangular. The moving part 8 is positioned by a spring 16.
According to one aspect of the present invention, a linear actuator includes a stator having a facing surface, at least one moving part having a facing surface, a coil provided in the stator, at least one moving part, and an elastic member elastically supporting the at least one moving part. The at least one moving part is provided such that the facing surface of the at least one moving part faces the facing surface of the stator. The at least one moving part is linearly movable with respect to the stator. At least one permanent magnet is provided in one of the stator or the at least one moving part and has a magnet surface facing the facing surface of another of the stator or the at least one moving part. A cross-sectional area of the at least one permanent magnet along a first plane substantially in parallel with the facing surface of the one of the stator or the at least one moving part reduces toward the magnet surface.
According to another aspect of the present invention, an electric appliance including a linear actuator. The linear actuator includes a stator having a facing surface, at least one moving part having a facing surface, a coil provided in the stator, at least one moving part, and an elastic member elastically supporting the at least one moving part. The at least one moving part is provided such that the facing surface of the at least one moving part faces the facing surface of the stator. The at least one moving part is linearly movable with respect to the stator. At least one permanent magnet is provided in one of the stator or the at least one moving part and has a magnet surface facing the facing surface of another of the stator or the at least one moving part. A cross-sectional area of the at least one permanent magnet along a first plane substantially in parallel with the facing surface of the one of the stator or the at least one moving part reduces toward the magnet surface.